Lewis Structures|Dot Structures – Drawn for phosgene (COCl2) -Ex. #6

A simple procedure for writing Lewis structures is given in a previous article entitled “Lewis Structures and the Octet Rule”. Relevant worked examples were given in the following articles: Examples #1, #2, #3 , #4 and #5.

A few more examples for writing Lewis structures following the above procedure are given bellow:

Let us consider the case of  phosgene COCl₂ :

Step 1: The central atom will be the C atom since it is the less electronegative. Connect the atoms with single bonds:

Step 2: Calculate the # of electrons in π bonds (multiple bonds) using formula (1) in the article entitled “Lewis Structures and the Octet Rule”. 

Where n in this case is 4 since COCl₂ consists of four atoms.

Where V = (4 + 6 + 7 + 7) = 24  

Therefore, P = 6n + 2 – V = 6 * 4 + 2 – 24 = 2      \  there are 2 π electrons in COCl₂  \

1 double bond must be added to the structure of Step 1.

Step 3 & 4: One double bond must therefore be placed to the structure in Step1. Therefore, the Lewis structures for COCl₂ are as follows:

Figure 1: Lewis structures for COCl₂. Resonance structure 2 is the most probable one since the there is no charge separation.